1. Field of the Invention
The present invention relates to a rotating apparatus for top ends of cans, which is utilized in, for example, automatic inspection of multiple features, such as external defects on the top ends, dimensional errors thereof, and so on, and more particularly to an improvement in the holding accuracy of the top ends of cans.
2. Prior Art
When manufacturing top ends of cans which are used for beverage containers, automatic inspection is essential for confirming dimensions of the manufactured top ends, existence of defects thereon, and an attached or fixed condition of retained caps mounted respectively on the top ends.
Conventionally, the top ends to be inspected are conveyed along a straight line by a conveyer or the like, and are inspected for their defects or the like by means of image processing devices arranged along the conveyer.
Each of the top-end holding platforms of the conventional rotating apparatus is constructed as shown in FIG. 18 or in FIG. 19. In this connection, a top end K has front and rear faces, and first and second annular projections KC and KD. The first annular projection KC is provided on the rear face and projects in an axial direction of the top end. A recess KA is defined by the first annular projection KC. The second annular projection KD like a flange is provided on the front face and projects perpendicularly to the axial direction. A recess KB is defined by the second annular projection KD. A retained cap R is formed on a bottom surface of the recess KB.
First, in the rotating apparatus shown in FIG. 18, a top-end holding platform 1 is formed at its upper face with a projection 1A which is fitted without gaps in the recess KA in the rear face of the top end K, and the top end K is centered by the projection 1A.
On the other hand, a top-end holding platform 11 shown in FIG. 19 is formed at its upper face with a projection 11A which is fitted without gaps in the recess KB in the front face of the top end K. The top end K is held on the top-end holding platform 11 in a reverse fashion, and is centered by the projection 11A.
Any of the conventional top-end holding platforms shown in FIGS. 18 and 19 are constructed such that the top end K is centered by the projection 1A or 11A. Because of such construction, in order to obtain sufficient accuracy, the projection 1A or 11A must be formed into such dimensions that the projection 1A or 11A is in close contact with a peripheral wall surface of the recess KA or KB. However, this produces the following disadvantage. That is, if the projection 1A or 11A is set to such strict or precise dimensions, a higher accuracy is required to cause the top end K to rest on the top-end holding platform 1 or 11 and to manufacture dies for molding the top end K. so that there is difficulty in supplying the top end to the top-end holding platform 1 or 11 and in manufacturing the top end K itself. For this reason, it is difficult to improve the centering accuracy of the top end K at inspection, and therefore the top-end holding platform 1 or 11 cannot accommodate recent trends toward ever-improving precision.
Furthermore, in the construction shown in FIG. 19 in which the top end K is held on the top-end holding platform 11 in a reverse fashion, it is impossible to confirm the fixed state of the retained cap R, which is one of the important inspected features. For this reason, inspection of the fixed condition of the retained cap R must be carried out separately, resulting in poor efficiency.
In addition, the above-described rotating apparatus comprises a top-end supply device provided for individually and successively supplying a plurality of top ends stacked one upon the other, from one thereof which is located at the front row, to feed the top ends to various inspecting instruments.
Conventionally, the operating speed of the rotating apparatus has been relatively low. Accordingly, in the supply of the top ends to the various inspecting instruments, the top ends have been delivered horizontally by a feeder or the like so that the top ends are supplied one by one to the inspecting instruments.
In recent years, however, in order to improve productivity, consideration is being given to instruments for automatically inspecting top ends continuously at high speed, that is, at several hundreds of top ends per minute, which is considerably faster than the conventional speed.
For the reason discussed above, the top-end supply device in which top ends are fed one by one horizontally by a feeder, or the like, have a limited operating speed. Thus, it is difficult to follow the high speed of the rotating apparatus.
Furthermore, the above rotating apparatus includes a top-end ejection device provided for ejecting the inspected top ends to a subsequent step at high speed.
The ejection device comprises an actuator such as a pneumatic cylinder, or the like mounted on the lateral side of a transport path defined along the outer periphery of the turntable, and the top ends are pushed out of the transport path into and along an ejection passage.
In the top-end ejection device in which reciprocal movement of the actuator causes the top ends to be ejected into the ejection passage, however, the pushing operation of the actuator with respect to the top ends must be quickly accompanied by an increase in the operating speed of the rotating apparatus. Accordingly, there is a concern that top ends may be damaged due to the impact of the reciprocal movement of the actuator. Further, vibration and noise from the ejection device are severe, and the cost required for driving the ejection device increases. Thus, a high-speed ejection device for the top ends, which is fundamentally new, is necessary.